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Aims: The optimal timing for implementing mechanical circulatory support (MCS) in cardiogenic shock (CS) remains indeterminate. This study aims to evaluate patient characteristics and outcome associated with the time interval between CS onset and veno-arterial extracorporeal membrane oxygenation (VA-ECMO) implementation., Methods and Results: In this study, patients with CS treated with MCS at 15 tertiary care centres in three countries were enrolled. Patients treated with MCS were stratified into early (<2 h), intermediate (2-12 h) and delayed (≥12-24 h) MCS implantation by using the time interval between CS onset and MCS device implementation. Adjusted logistic and Cox regression models were fitted to assess the association between timing of MCS implementation, patient characteristics and 30-day mortality. A total of 330 patients with CS treated with VA-ECMO and/or microaxial flow pump were included in this study; 20.9% received early, 55.8% intermediate, and 23.3% delayed MCS. Although crude 30-day mortality was slightly lower in patients with early MCS (58.1% vs. 64.7% vs. 64.3%), adjusted analyses showed no significant association between timing of MCS implantation and 30-day all-cause mortality (hazard ratio [HR] for early vs. intermediate MCS: 0.93, 95% confidence interval [CI] 0.59-1.46, p = 0.74; HR for early vs. delayed MCS: 1.29, 95% CI 0.78-2.13, p = 0.33). Moreover, the incidence of complications, related and unrelated to MCS, did not differ significantly among groups., Conclusion: In this exploratory study of patients with CS treated with MCS, the timing of device implantation within 24 h after CS onset was not associated with mortality. This supports a restrictive MCS approach, reserving its application for patients experiencing CS deterioration despite conventional therapy., (© 2024 The Author(s). European Journal of Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Aims: Veno-arterial extracorporeal membrane oxygenation therapy (VA-ECMO) restores circulation and tissue oxygenation in cardiogenic shock (CS) patients, but can also lead to complications. This study aimed to quantify VA-ECMO complications and analyse their association with overall survival as well as favourable neurological outcome (cerebral performance categories 1 + 2)., Methods and Results: All-comer patients with CS treated with VA-ECMO were retrospectively enrolled from 16 centres in four countries (2005-2019). Neurological, bleeding, and ischaemic adverse events (AEs) were considered. From these, typical VA-ECMO complications were identified and analysed separately as device-related complications. n = 501. Overall, 118 were women (24%), median age was 56.0 years, median lactate was 8.1 mmol/L. Acute myocardial infarction caused CS in 289 patients (58%). Thirty-days mortality was 40% (198/501 patients). At least one device-related complication occurred in 252/486 (52%) patients, neurological AEs in 108/469 (23%), bleeding in 192/480 (40%), ischaemic AEs in 123/478 (26%). The 22% of patients with the most AEs accounted for 50% of all AEs. All types of AEs were associated with a worse prognosis. Aside from neurological ones, all AEs and device-related complications were more likely to occur in women; although prediction of AEs outside of neurological AEs was generally poor., Conclusion: Therapy and device-related complications occur in half of all patients treated with VA-ECMO and are associated with a worse prognosis. They accumulate in some patients, especially in women. Aside from neurological events, identification of patients at risk is difficult, highlighting the need to establish additional quantitative markers of complication risk to guide VA-ECMO treatment in CS., Competing Interests: Conflict of interest: Dr Bernhardt reports personal fees from Abbott, personal fees from Abiomed, personal fees from Astra Zeneca, personal fees from Berlin Heart, personal fees from Fine Heart, personal fees from Medtronic, outside the submitted work; Dr Morrow reports grants and personal fees from Abbott Laboratories, grants from Abiomed, grants from Amgen, grants from Anthos Therapeutics, grants from ARCA Biopharma, grants from AstraZeneca, grants from Bayer Healthcare, grants from Eisai, grants, and personal fees from Merck, grants and personal fees from Novartis, grants from Pfizer, grants from Regneron Pharmaceuticals, grants and personal fees from Roche Diagnostics, grants from Siemens, personal fees from InCardia, personal fees from Inflammatix, outside the submitted work; Dr Varshney reports personal fees from Broadview Ventures, outside the submitted work. The other authors report no conflicts of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Engineered antibodies with pH responsive cell surface target antigen-binding affinities that decrease at the acidic pH (5.5-5.8) within the endosomes have been found to have reduced susceptibility to degradation within the lysosomes and increased serum half-life. Such pH responsive recombinant antibodies have been developed for the treatment of cancer and cardiovascular disease. Engineered tenth type III human fibronectin (Fn3) domains are emerging as a class of target antigen-binding biopharmaceuticals that could complement or be superior to recombinant antibodies in a number of biomedical contexts. As such, there is strong motivation for demonstrating the feasibility of engineering Fn3s with pH responsive antigen binding behavior that could lead to improved Fn3 pharmacokinetics., Results: A yeast surface-displayed Fn3 histidine (His) mutant library screening approach yielded epidermal growth factor receptor (EGFR)-binding Fn3 domains with EGFR binding affinities that markedly decrease at endosomal pH; the first reported case of engineering Fn3s with pH responsive antigen binding. Yeast surface-displayed His mutant Fn3s, which contain either one or two His mutations, have equilibrium binding dissociation constants (KDs) that increase up to four-fold relative to wild type when pH is decreased from 7.4 to 5.5. Assays in which Fn3-displaying yeast were incubated with soluble EGFR after ligand-free incubation in respective neutral and acidic buffers showed that His mutant Fn3 pH responsiveness is due to reversible changes in Fn3 conformation and/or EGFR binding interface properties rather than irreversible unfolding., Conclusions: We have established a generalizable method for efficiently constructing and screening Fn3 His mutant libraries that could enable both our laboratory and others to develop pH responsive Fn3s for use in a wide range of biomedical applications.

In the sera of four female patients with proven IgG-linked creatine kinase BB (macro creatine kinase BB) we studied the nature of the binding between creatine kinase isoenzymes and immunoglobulin G. The specificity towards the isoenzyme bound, the recombination of the complex after treatment with acid buffer, the site of the binding between both partners and an apparently monoclonal nature of the immunoglobulin G involved in the complex indicate that a specific antigen-antibody reaction is responsible for the existence of macro creatine kinase BB in the sera investigated.